The volcano that already erupted in Iceland will continue to disturb European weather paterns, but the effect is not expected to spread beyond Europe

The volcano that already erupted may be a signal that an eruption of the much larger volcano "Katla" is coming. In the past, Katla erupts about every 80 -90 years, and is now overdue. Its past eruptions have been preceeded by an eruption of the smaller volcano that already erupted just over a week ago

If Katla erupts, the eruption is expected to be much larger and will affect weather in the entire northern hemisphere, for a longer period of time. A Katla eruption should therefore be expected to have a much more severe impact on the global economy than the eruption that has already occurred.

Ok, so far, very interesting. But the essential questions nobody seems to be reporting on include:

When they say Katla typically erupts after the volcano that just erupted, what does that mean in time scale? Does Katla typically erupt hours after the smaller volcano? Days? Months? A year later?

After what period of time would it be reasonable to assume that if no Katla eruption has occurred, that the risk of a "related" eruption has subsided? Days? Weeks? Months? Years?

I'm picturing a Kata eruption probability curve. It shows that for a certain time after the first eruption, Katla's eruption probability increases to some definitive probability percentage, then decreases with time until enough time has passed that a "related eruption risk" has subsided. Does anyone know where to find this graph?

If not the probability graph, how'bout just the basic information of how long the interval between eruptions has been historically? In other words, in the past Katla has erupted _____% of the time following an eruption of the smaller volcano. The minimum time from the smaller eruption to the Katla eruption was _____, the maximum was _____, and the expected mean is _____.

Don't have that data, but there are a few more points of information in this article, which you may well have already seen:

Scientists are watching Katla closely. There is a good chance it may soon erupt. In the past three eruptions of Eyjafjallajokull, Katla soon erupted too, reports the Huffington Post.

It is not yet known if the Eyjafjallajokull volcano is done erupting yet. The 1821 eruption of this volcano was ongoing for about 13 months, notes the Detroit Free Press.

The Katla volcano is located just 12 miles east from Eyjafjallajokull. Scientists note that Katla is overdue for an eruption. This volcano typically erupts every 80 years. Its most recent eruption was in 1918. If Katla erupts it could cause climate changes throughout much of the world.

The Katla volcano is covered by a huge glacier named Myrdalsjokull. If Katla erupts a mix of lava and icy cold water from the glacier could cause blasts that would make ash explode to high altitudes. The Detroit Free Press notes that "A Katla eruption would be 10 times longer and shoot higher and larger plumes of ash than its smaller neighbor."

USA Today reports that when Katla exploded in the 1700s it caused a frigid winter in America, according to Gary Hufford, a scientist with the Alaska Region of the National Weather Services. He stated that "The Mississippi River froze just north of New Orleans, and the East Coast, especially New England, had an extremely cold winter."

But the first links provide the best summary (and you can find lists of articles about each volcano) and is a great resource. I think the evidence for the link between the two is suggestive but not predictive and would rate the probability at better than 50% for an eruption of Katla within 2 years. Remember though that there are many other volcanoes in the area and that world-wide the probability of major eruption that has some disruptive effect in not negligible. Predictive power is usually poor until an eruption is imminent - and even then the nature of the eruption is hard to predict. There have been a few successes (Pinatubo, St. Helen's) and many surprises and failures in the business...

The probability that the Yellowstone caldera will erupt again is high.... sometime in the next 10,000 years... Given that the frequency is every ~600,000 years and as they say in the video the people studying it have no modern analog to help understand how the process occurs any prediction is a shot in the dark. That being said the paleo record is full of interesting clues about strange events that have occurred in the past that humans have no living memory of or documented occurrence of. The likelihood is that we will be surprised by some event that was not on the radar rather than something that was anticipated or predicted. The probability that we will be surprised I would rate as very high - nearly a certainty.

I did some more digging. Not a whole lot more, but got a little better info. For the benefit of others interested in this:

It sounds like the rough time window during which Katla has increased eruption probability after Eyjafjallajokull erupted is about a year. Last time was about 6.5 months between them.

The data on volcanoes in general says these correlations are very unreliable. What happened last time is not all that likely to happen this time because the underground magma channels that control all this tend to be redefined by each big eruption.

If Katla blows big-time, the melting-of-ice aspect will be enormous, and the ash blast into the upper atmosphere will be much more serious than the recent Eyjafjallajokull eruption.

Last time this happened, there were major, cataclysmic floods in populated areas within hours after the eruption began

Nobody knows for sure how long the current Eyjafjallajokull eruption will last. Apparently for one of these things to erupt continuously for a year or two is not out of the ordinary

My take is that there is no particularly ripe speculative investment play at this time. Going long agricultural commodities would be the obvious play - the world crops would be screwed if Katla had a major eruption and ags would skyrocket. But I think the probability of reality sinking in and the economy taking a nosedive in the next 6 months is pretty high. That said, a long ag play would likely be wiped out by the economic downturn before the maybe-maybe-not Katla event would likely happen.

Im sure USA Today refered to the destructive Laki-Eruption , which is a system nearby Katla, and which killed 75% of icelands livestock and 25% of all peoples. Katla hasnt been that destructive in historic times.

When I was in Iceland last summer, they had evacuation plans all over the area around Katla, they are indeed expecting an eruption, and are mostly afraid of the floodings.

There is some information about the monitoring of icelandic volcanoes at the Institute of Earth Sciences. For a forecast it would be interesting to compare the data collected before the Eyafjallajökull eruption, and the measurements at Katla.